Catching Rays: Time for an Airshower

The second comp, with the writer’s text used in the callouts. The green box will become a map of Mexico with the location of the observatory site.

It’s time to make a new comp. The writer’s text has been inserted and the callouts adjusted to fit. The water tank cutaway is in place. (You may notice some differences between this water tank and the one shown in the previous post. The comp shows an earlier version, since corrected.)

As I suspected, the cumulus clouds interfere with the introductory text. They’ll have to go. I’m not happy with the arrangement of the other callouts, but we can address that later.

(Infographic Rule No. 1: Never hesitate to put off decisions that you’re not ready to make. Sometimes you just need more information.)

It’s time to build the air shower.

An air shower is produced when a high-energy cosmic ray particle enters the atmosphere. When it collides with air molecules, it splits into new particles. The new particles, in turn, create more particles, producing a cascade that continues to grow and lose energy. As it approaches the surface of the earth the cascade becomes an ever-expanding “pancake” of low-energy particles.

This is what the observatory is designed to detect: Particles in the pancake strike the water tanks and emit ultraviolet radiation. The UV light is measured by the photosensors in the bottom of each tank. By studying the strike rate and pattern, scientists can deduce the particles’ type, energy, and other information.

How to illustrate this?

We’ll use two images: One to show the initial atmospheric strike, and another to illustrate the expanding particle pancake.

The particle cascade model, viewed in Maya’s 3D window.

Maya includes tools that can be used to create shapes that simulate foliage and other kinds of organic shapes. Including (in this case) the paths of subatomic particles as they split and zip through the atmosphere. It takes only a few minutes to create a convincing particle cascade.

The pancake is more of a challenge, since the particles will need to be shaped in a specific way. For this we’ll create a NURBS model, funnel-shaped to show how the pancake widens as it approaches the ground. We’ll use the model as a particle emitter to generate a cloud of particles.

In modeling and animation, 3D particles are used to simulate smoke, dust, fire and other sophisticated special effects. But we need just a simple snapshot of a simple particle cloud.

Here is our model, a simple NURBS surface . . .

Funnel-shaped model that will be used to create the particle cloud for the gamma-ray “pancake.”

. . . and here it is again after being set up as a particle emitter. The cloud of particles is emitted over time; in other words, over a series of frames used to create this animation. We don’t need the animation, of course. We’ll just grab a single frame and use that.

Animation loop showing how the particle cloud is emitted over time.

To make sure that everything will line up, we’ll use the second comp as a background image in Maya, then align it with the cascade and particle models. Right away, we can see that it’s getting crowded near the top and on the right side of the graphic. We’ll have to rearrange things. But the angle and size of the new models look good, so we’ll render black-and-white images of each one.

The second comp, placed as a background image in Maya, with the cascade and pancake in place.

These are the final two pieces of the model. We’re ready to start putting everything together.